1. Field of the Invention
The present invention relates to regulating the output of switching power supplies.
2. Related Background Art
Japanese Patent Application Laid-Open No. HEI 11-75366 and No. 2001-251851 disclose switching power supplies which can statically change the output voltage according to the species of the load to apply the output voltage.
Recently, switching power supplies such as DC/DC converters have been required to improve their rising characteristics at the time of starting and dynamically change their output voltage while a load to apply the output voltage is operating. In terms of the rising characteristics at the time of starting, an increasing number of loads have been restricted such that no period with a decreasing output voltage exists until the output voltage reaches a target value upon starting the power supplies. Examples of such loads include PLD, DSP, and CPU. Also, an increasing number of loads have been strictly restricted in terms of rising time. Therefore, it has been desired to change the output voltage monotonously and rapidly. Regarding dynamically changing the output voltage while the load operates, ICs which can suppress the power consumption by applying a dynamically variable output voltage to the load have been under development.